danw
Lifetime Supporting Member
what would be the output range of the rtd?
is it analog current or vlotage(4-20mA or 0-10V).
An RTD is a positive temperature coefficient element that changes resistance with temperature. The controller pumps a constant current through the resistor which develops a voltage (IR) drop which the controller 'reads' and converts to a temperature value. The Platinum Pt100 is the most common industrial RTD.
A 2 wire RTD ALWAYS as a positive error due to the resistance of the copper lead wires. Always use a 3 wire RTD because a UDC can handle a 3 wire and the 3rd wire allows the controller to compensate for lead wire resistance.
how can i loop the rtd to honeywell loop controller? directly can i connect the (3 wire or 2 wire) from pt100 rtd to UDC3500 controller or in between i need to use any temperature transmitter?
You connect a 3 wire RTD to the controller with 3 copper wires of equal length. The cable is called Triad for 3 conductor. Sometimes people use two twisted pair cables for a total of 4 conductors and don't use one of the conductors. RTD cable should always have twisted shielded conductors because it is a very low level signal.
There is no external power needed for an RTD. The controller does what it needs to do to 'excite' the RTD and read the IR value.
No, PT1000 is HVAC, PT100 is industrial. The UDC is an industrial controller designed for a Pt100.can i use pt1000 rtd instead of pt100 rtd? pt1000 is available in honeywell.
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1) Use a 3 wire RTD, and say "3 wire RTD". No choice for 2 wire . Bad Juju.attached the schematic i made for your kind info sir. please see the link. http://i64.tinypic.com/2cwlyzm.png
2) 'Feedwater' is a term usually associated with boilers. If the control is cooling control, why not call it cooling supply line, or something like that? The arrow might point to the rooms, because that's where it is presumably used, since that's the temperature you're measuring.
3) "Position feedback" is not the same as a 4-20mA control signal. The controller generates a 4-20mA control signal which is position demand signal. Some actuators have an optional 4-20mA feedback with the actuator generates and the controller reads, but I doubt that's the case here.
It should read: A1) Use a 3 wire RTD, and say "3 wire RTD". No choice for 2 wire. Bad Juju.
2) 'Feedwater' is a term usually associated with boilers. If the control is cooling control, why not call it "cooling supply line", or something like that? The arrow might point to the rooms, because that's where the cooling is presumably used, since that's where you're measuring and controlling the temperature.
3) "Position feedback" is not the same as a 4-20mA control signal. The controller generates a 4-20mA control signal which is position demand signal. Some actuators have an optional 4-20mA feedback with the actuator generates and the controller reads, but I doubt that's the case here.
It should say: Actuator with a 4-20mA control signal
4) Get rid of the word "feedforward". The math option is a summer. There is no feedforward control.
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